1. Field of the Invention
The present invention relates to a composite pull-chain disc mechanism with a brake function for a door operator, and particularly, to an electric door operator incorporated with this composite pull-chain disc mechanism for operating in a manual mode through the composite pull-chain disc mechanism.
2. Description of the Related Art
Generally, a door operator used in, such as a fireproof door or a safety door, basically has an electric motor mechanism to drive a rotating shaft so as to wind a door curtain. A brake mechanism is incorporated for braking the rotating shaft, a pull-chain disc mechanism is used to manually rotate the rotating shaft by means of a pull chain under power failure condition, and an electric clutch mechanism is used to release the brake mechanism or connect the pull-chain disc mechanism by an electromagnet. Furthermore, a lock device for stopping the rotation of the pull-chain disc in an electric operation mode is included, and a brake releasing device is used to release a brake in a manual operation mode.
It is known that a plenty of documents related to door operators are proposed. For example, U.S. Pat. No. 6,092,582 has disclosed the above-described type operation mode, wherein in a manual operation mode, on one hand, a lock device for a pull chain is first released; on the other hand, a brake for the rotating shaft of a door operator is released by a brake releasing device by using a mechanical force, and then, the pull chain is pulled to rotate a pull-chain disc and renders the rotating shaft to rotate. The above-mentioned patent has not only a complicated structure, but also quite inconvenient for operation. In general, once an electric motor mechanism is detached during maintenance for the door operator, a manual mechanism becomes invalid, and hence normal personnel access is affected.
In U.S. Pat. No. 6,055,885 issued to the present applicant, except that a pull-chain disc is used in a manual operation mode under power failure circumstance, the rotation of the pull-chain disc is usually limited by a pull chain, which is locked by a locking device disposed on the housing of a door operator. Therefore, in the case that an electromagnet is not magnetically excited, the pull-chain disc also functions as a brake disc for braking the rotation of the rotating shaft of the door operator. Moreover, in the case that an electric motor mechanism is detached during maintenance, the door operator can still be operated in a manual mode to keep normal personnel access.
Moreover, the present inventor, in U.S. Pat. No. 7,055,283 B2, proposes a control system for switching an electric operation to a manual operation of a door operator, the control system comprising a brake device, used for braking and releasing a rotating shaft of the door operator; a pull-chain disc device, pivoted about a different axle; a clutch device, disposed between the rotating shaft and the pull-chain disc, used for driving the rotating shaft in one direction; a driven disc, linked with the clutch device so as to switch a protective device. As long as the pull chain is pulled, the protective device cuts off an electric circuit for the door operator and releases brake to automatically switch the door operator to a manual mode.
For those skilled in the art there are still spaces for the above-mentioned patents to improve in terms of their usages and structure.